RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage tumor cells. Combining radiation therapy with chemotherapy may kill more tumor cells. It is not yet known which treatment regimen is most effective for pancreatic cancer.

PURPOSE: Randomized phase III trial to compare the effectiveness of fluorouracil and gemcitabine plus radiation therapy in treating patients with cancer of the pancreas who have undergone surgery.

OBJECTIVES:

• Compare the overall and disease-free survival of patients with resected adenocarcinoma of the pancreas treated with adjuvant fluorouracil-based chemoradiotherapy preceded and followed by fluorouracil vs gemcitabine.
• Compare the local-regional and distant disease control in patients treated with these regimens.
• Compare the acute and late toxic effects of these regimens in these patients.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to nodal involvement (yes vs no), tumor diameter (less than 3 cm vs 3 cm or greater), and surgical margins (negative vs positive vs unknown). Patients are randomized to one of two treatment arms.

• Arm I: Beginning 3-8 weeks after definitive surgical resection, patients receive fluorouracil IV continuously for 3 weeks. Beginning 1-2 weeks later, patients receive fluorouracil IV continuously concurrently with radiotherapy 5 days a week for 5.5 weeks. Beginning 3-5 weeks after completion of chemoradiotherapy, patients receive fluorouracil IV continuously for 4 weeks every 6 weeks for 2 courses.
• Arm II: Beginning 3-8 weeks after definitive surgical resection, patients receive gemcitabine IV once weekly for 3 weeks. Beginning 1-2 weeks later, patients receive chemoradiotherapy as in arm I. Beginning 3-5 weeks after completion of chemoradiotherapy, patients receive gemcitabine IV once weekly for 3 weeks every 4 weeks for 3 courses.

Patients are followed every 3 months for 1 year, every 6 months for 2 years, and then annually thereafter.

PROJECTED ACCRUAL: A total of 518 patients will be accrued for this study within 8.6 years.

DISEASE CHARACTERISTICS:

• Histologically confirmed adenocarcinoma of the pancreas

  • Stage T1-4, N0-1 (stage I-IVA)
  • No M1 or NX staging
  • Primary tumor of the pancreas (pancreatic head, neck, uncinate process, or body/tail) and maximum diameter/dimension and tumor status at surgical margin known

• Prior potentially curative gross resection within 3-8 weeks before study

• No non-adenocarcinomas, adenosquamous carcinomas, islet cell carcinomas, cystadenomas, cystadenocarcinomas, carcinoid tumors, duodenal carcinomas, distal bile duct carcinoma, or ampullary carcinoma

• No recurrent disease

• Post-resection CA-19-9 level required

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 60-100%

Life expectancy:

• Not specified

Hematopoietic:

• WBC at least 3,000/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• SGOT no greater than 5 times ULN

Renal:

• Creatinine no greater than 1.5 times ULN

Other:

• No significant nausea or vomiting

• No prior malignancy within the past 5 years except nonmelanomatous skin cancer or carcinoma in situ of the cervix

• Able to maintain adequate nutrition (at least 1,500 calories/day)

  • Feeding tube allowed

• Not pregnant

• Negative pregnancy test

• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No prior chemotherapy

Endocrine therapy:

• Not specified

Radiotherapy:

• No prior radiotherapy

Surgery:

• See Disease Characteristics